JP2007514018A - Novel storage-stable photocurable coating composition - Google Patents

Abstract

Blends of epoxy-terminated silicone and carbinol-terminated silicone polymers with alkylphenol and iodonium photocatalyst additives form a one-part ultraviolet or electron beam curable release coating composition with storage stability.
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Description

  The present invention relates to an improved UV curable silicone release coating composition. More specifically, the present invention relates to blends of telechelic reactive organofunctional polydiorganosiloxane silicone polymers with alkylphenols and compatible onium type photocatalysts.

  Silicone coating compositions are useful for many applications, including release (tack-free) coatings, protective coatings, and conformal coatings. These coatings are often applied to a substrate as a dispersion in a solvent system or an emulsion in water in order to reduce the viscosity sufficiently so that the coating composition can be easily applied. The presence of the solvent, whether water or a suitable low boiling organic solvent, requires that they be evaporated. Therefore, the heating of the silicone-coated product has served two purposes: solvent removal and heat curing. It is desirable to eliminate the solvent for two important reasons: Certain organic solvents are harmful to the environment and / or safety, and the energy required to produce the coated product is reduced if the evaporation operation is eliminated. If there is no need for a thermosetting step, another curing mechanism such as irradiation curing using either actinic radiation or electron beam irradiation can be considered.

  If no organic solvent is present in the coating composition, costly contaminant removal equipment is not required and the energy required for curing is reduced. As long as certain silicone coating compositions are thick and viscous mixtures that are difficult to apply unless the viscosity is reduced by solvent dilution, the absence of solvent creates disadvantages. Therefore, with such materials it is difficult to obtain a uniform and thin coating without defects. Certain photocatalysts, particularly polar onium type photocatalysts, may require the presence of a compatibilizing solvent so that they can be dissolved in the nonpolar silicone coating mixture.

Silicone compositions have been used for a long time to impart non-tackiness to surfaces that would normally stick. For example, epoxy functional silicones taught in US Pat. No. 4,279,717 are known to be useful for release coatings in combination with certain compatible iodonium cationic photocatalysts. Epoxy silicone release coatings can be processed at high speed with minimal energy consumption. When the viscosity of the coating composition exceeds 1000 centistokes (cstk) at room temperature, the composition is difficult to apply, especially in the absence of a solvent in the composition, especially when a thin coating of about 1 gm / m ² is desired. . Viscosity constraints due to processing equipment limit the molecular weight of the silicone composition and linear functionalized photocurable liquid silicones such as epoxy silicones. The need for miscibility or solubility of the photocatalyst, rapid photocuring response, and good release performance add additional constraints. High epoxy content in the epoxy silicone as the epoxy functional group of the linear silicone molecule tends to improve the compatibility of the onium photocatalyst with the silicone and rapid photocuring, but it is peeled off with premium properties, i.e. small force The properties to be required require a low epoxy content.
US Pat. No. 4,279,717 US Pat. No. 5,258,480 US Pat. No. 5,814,679 US Pat. No. 5,034,491

  It would be highly desirable if the ease of use of the solventless silicone release coating composition could be improved by providing a coating material, such as a one-part product, that can be used immediately without mixing reactive components at the time of use. Thermosetting silicone release agents cannot be formulated as a one-part product due to their inherently short mixing pot life, but for photocurable silicone release agents, the formulated mixture is crosslinked under normal storage conditions under non-exposure ( If it is stable for a long time without causing (curing) reaction, it can be provided as a one-pack type product. Conventional multifunctional epoxy silicones result in unstable UV curable coating compositions when blended with onium-type catalysts, causing poorly miscible iodonium catalysts to deposit from the suspension over time or prior to use. The polymer is cross-linked and becomes useless to the user.

The present invention relates to certain telechelic reactive silicones, i.e. linear polydialkylsiloxanes having reactive functional groups at the chain terminator sites but no reactive functional groups at other sites in the polymer chain. When combined with additives and compatible iodonium salt photocatalysts, a surprisingly stable photocurable composition that can be easily applied to conventional substrates and that cures efficiently upon exposure to ultraviolet light to yield a tack-free coating. Based on the knowledge of giving.
The composition of the present invention, when applied and cured, provides unmatched useful properties and performance with respect to release properties and release performance from conventional pressure sensitive adhesives (PSAs) in the form of tapes or labels.

Accordingly, the present invention provides an ultraviolet or electron beam curable silicone coating composition comprising the following components a) to d).
_{^{a) M E D x M E}} , a ^_M GE ^D x _{M GE,} epoxy terminated linear silicone selected from ^_M E D ^x _M ^GE and mixtures thereof, from about 10 to about at 25 ° C. 1000 Epoxy-terminated linear silicone with centistokes viscosity, where M ^E = (C ₆ H ₉ O (CH ₂ CH ₂ ) (CH ₃ ) ₂ SiO _1/2
M ^GE = (CH ₂ (O) CH) O (CH ₂ ) ₃ (CH ₃ ) ₂ SiO _1/2
D = (R ¹ ) ₂ SiO _2/2 ,
x is 0 or a positive integer, and R ¹ is a C _{1 to} C ₆₀ monovalent hydrocarbon group. ),
b) Carbinol functional silicone, preferably selected from the group consisting of M ^ROH D _y M ^ROH , where M ^ROH is HO (CH ₂ ) ₃ (CH ₃ ) ₂ SiO _1/2 , (HOCH ₂ ) ₂ (C ₂ H ₅ ) C (CH ₂ ) ₃ (CH ₃ ) ₂ SiO _1/2 and HOCH ₂ CH (OH) CH ₂ O (CH ₂ ) ₃ (CH ₃ ) ₂ SiO _1/2 Y is an integer such that the viscosity of the carbinol-functional silicone at 25 ° C. is about 50-5000 cstk).
c) An effective amount of a bis (alkylphenyl), alkylphenyl (phenyl) or alkoxyphenyl (phenyl) iodonium salt photocatalyst comprising hexafluoroantimonic acid, hexafluoroarsenic acid, hexafluorophosphoric acid, tetrafluoroboric acid, tetra ( A photocatalyst selected from salts of the group of acids consisting of perfluorophenyl) boric acid and mixtures thereof,
_{d) R b -C 6 H 5} -b -OH alkylphenol compound selected from the group consisting of (wherein, R _C 1 _{-C 60} straight chain _alkyl, C 3 _{-C 60} branched _{alkyl, C} 2 ~ Independently selected from monovalent hydrocarbon groups selected from the group consisting of C ₆₀ straight chain alkenyl and C ₃ -C ₆₀ branched alkenyl groups, wherein the R group is α-, β- to the phenolic OH functionality. Or γ-position, and b = 1, 2, 3, 4 or 5. When b is 2 or more, “independent selection” means each of the C ₆ H _5-b nuclei. It means that the R substituents may be the same or different.

  Subscripts x and y of the telechelic reactive silicone polymer can be variously varied, and the relative amount of each telechelic functional silicone polymer can also be varied with the condition that it provides a viscosity within the desired range.

  The epoxy-functional liquid polydiorganosiloxane provided in the present invention is more specifically a dialkyl epoxysiloxy-terminated polydialkylsiloxane polymer. The carbinol-functional polydiorganosiloxane liquid is more specifically a dialkyl (HOR) siloxy-terminated polydialkylsiloxane polymer, wherein each chain terminator unit (terminal siloxy) is terminal silicon atom via a hydrocarbon linking group. And having one or more terminal hydroxy groups bonded thereto.

  The epoxy functional group is a hydrosilylation addition of a hydrogen atom of a dialkylhydrogensiloxy chain terminator group with an organic molecule having both ethylenic unsaturation and an epoxide functional group, as taught in US Pat. No. 5,258,480. Obtained by reaction.

  The carbinol functional group is similar to the hydrogen atom of a dialkylhydrogensiloxy chain terminator group, as taught in US Pat. No. 5,814,679, with an organic molecule having both a HO—R— group and ethylenic unsaturation. It is obtained by reacting with

  The alkyl group of the telechelic reactive dimethyl-organosiloxy-terminated linear polydialkylsiloxane is preferably a methyl group. The ethylenically unsaturated epoxy or epoxide monomer is preferably an unsaturated alicyclic epoxy compound such as 4-vinylcyclohexene oxide (VCHO), vinyl norbornene monoxide, limonene monoxide or dicyclopentadiene monoxide. The ethylenically unsaturated carbinol or poly (carbinol) monomer is preferably allyl alcohol, mono-allyl ether of glycerol or mono-allyl ether of trimethylolpropane.

  The hydrosilylation reaction used for the functionalization of silylhydride-containing polysiloxanes is preferably catalyzed by trace amounts of Group VIII noble metal compounds. In this specification, the group VIII noble metal is defined as a group consisting of ruthenium, rhodium, palladium, osmium, iridium and platinum.

  The hydrogen functional siloxane precursor liquid may be selected from dimethylhydrogensiloxy-terminated polydimethylsiloxanes of any chain length including 1,1,3,3-tetramethylsiloxane.

Alkylphenols are well-known compounds and are widely used as additives in many plastic processing and applications. The most preferred alkylphenols for use in the present invention are compounds including 4-nonylphenol, 4-dodecylphenol (DDP) and 2-allylphenol. Commercially available DDP is usually a mixture of various alkylphenols having an alkyl group chain length of C _{10 to} C ₁₄ and contains not only a linear group but also a branched group.

  The chemical formulas of the compounds listed above were described without considering the positional isomerism of the substituents. Specific structural isomers of these general formulas are commercially available and specific examples thereof were used in the examples to illustrate the methods of practice and utility. Therefore, since it is predicted that geometric isomers having the same empirical formula and molecular formula are also sufficiently effective for the purpose of the present invention, these compounds are described in the general structure in the claims.

  This time, when the above-mentioned epoxy-terminated silicone polymer and carbinol-terminated silicone polymer diluted with alkylphenol are combined with a miscible bisaryliodonium catalyst, the resulting mixture can initiate a curing reaction by UV or electron beam irradiation, It has been found to form solid silicone release coatings incorporating photopolymerized silicone and alkylphenol. Also, because these specific reactive silicone polymer, alkylphenol and iodonium photocatalyst mixtures have an extremely long effective shelf life, this unique combination of materials requires no user mixing or other work. An unexpected finding that it can be produced as a liquid photocurable silicone product was also obtained. Further, the release performance characteristics of a fully cured coating of such a one-part UV curable composition is different from the release performance characteristics of a conventional multifunctional UV curable epoxy silicone release coating, and is a solventless thermosetting silicone coating. It was also found that a dynamic peel profile comparable to that obtained with Both the long effective shelf life and release performance of the compositions of the present invention are exclusively based on telechelic-structured reactive silicone polymers, ie, linear polydimethylsiloxane polymers having reactive organic functional groups only at the chain termination sites of the molecule. It is thought to be caused by this.

  Although the ultraviolet curable or electron beam curable epoxy functional silicone composition of the present invention is not particularly limited, super calendar craft (SCK) paper, glassine paper, polyethylene craft (PEK) paper, polyethylene film, polypropylene film and polyester film. Can be applied to cellulosic or plastic film substrates including The reaction initiated by electron beam or ultraviolet light cures the liquid silicone release coating to form a solid non-tacky or non-tacky release surface on the coated substrate.

  Acrylate functional silicones as taught in US Pat. No. 5,034,491 are also photocurable in the presence of a photoinitiator and can be formulated as a one-part photocurable release coating. In addition, stabilizers such as hydroquinone are typically required for photocurable acrylate silicone compositions that can be photocured in the presence of common radical photoinitiators. Typical conventional photoinitiators such as benzophenone and its derivatives, as well as stabilizers, are generally poorly soluble in silicone media. Due to the low solubility, problems arise regarding the proper choice of these necessary additives. Another problem with radical photocurable silicone systems is cure inhibition caused by the presence of oxygen, so that the coated substrate is exposed to an inert atmosphere such as nitrogen during UV irradiation for a rapid cure response. It is necessary to leave. While it is feasible to keep the UV or electron beam curing chamber in an inert atmosphere, the requirements for the inert atmosphere complicate the coating and curing process and are costly.

  Ultraviolet and / or electron beam curable epoxy silicone polymers as taught by Eckberg et al., US Pat. No. 4,279,717, have some compatible onium-type cationic properties without causing problems of inhibition in the presence of oxygen. Efficient curing in the presence of a photocuring catalyst has already been demonstrated. These epoxy silicone compositions maintain the need for a defect-free coating with a polymer thickness of about 0.5-2.0 μm and good adhesion to the substrate that can be applied to the substrate at high coating speeds. Due to the necessity of rapidly photocuring such a photocurable composition by ultraviolet exposure, the viscosity and epoxy content are limited to a narrow range.

  The three-roll offset gravure or multi-roll film splitting coating method commonly used for high-speed coating of solventless silicone requires that the viscosity of the silicone be in the range of 20 to 2000 centistokes at the coating temperature, Rapid curing requires the presence of a sufficient amount of reactive oxirane in the epoxysilicone molecule to promote dissolution of the onium type catalyst and ensure high system reactivity. If too much oxirane reacts in the liquid silicone composition, a photocured epoxy silicone composition with desirable release performance cannot be obtained.

The epoxy functional silicone compounded in the coating composition of the present invention is preferably selected from the following group.
_{^{a) M E D x M E}} , M GE D x M GE, M E D x M GE and epoxy functional silicone selected from the group consisting of epoxy terminated linear silicone selected from the group consisting of mixtures.
_{^{Wherein, M E = (C 6 H}} 9 O (CH 2 CH 2) (CH 3) a _{2 SiO 1/2,}
M ^GE = (CH ₂ (O) CH) O (CH ₂ ) ₃ (CH ₃ ) ₂ SiO _1/2
D = (R ¹ ) ₂ SiO _2/2 ,
x is 0 or a positive integer, the viscosity of the epoxy-terminated linear silicone at 25 ° C. is about 10 to about 1000 centistokes, R ¹ is a C ₁ -C ₆₀ monovalent hydrocarbon group, x is A positive integer, the epoxy functional silicone at 25 ° C. is about 10 to 1000 centistokes. R ¹ is preferably methyl.

The carbinol functional silicone compounded in the coating composition of the present invention is selected from the group consisting of M ^ROH D _y M ^ROH .
^{Wherein, M ROH} is _{HO (CH 2) 3 (CH} 3) 2 SiO 1/2, (HOCH 2) 2 (C 2 H 5) C (CH 2) 3 (CH 3) 2 SiO 1/2 and HOCH ₂ CH (OH) CH ₂ O (CH ₂ ) ₃ (CH ₃ ) ₂ SiO _1/2 is selected, y is an integer such that the viscosity of the carbinol-functional silicone at 25 ° C. is about 50-5000 cstk. is there.

The additional component is an alkylphenol compound selected from the group consisting of R _b —C ₆ H _5-b —OH. Wherein R is selected from the group consisting of C ₁ -C ₆₀ straight chain alkyl, C ₃ -C ₆₀ branched alkyl, C ₂ -C ₆₀ straight chain alkenyl and C ₃ -C ₆₀ branched alkenyl groups. Independently selected from monovalent hydrocarbon groups, the R group may be in the α-, β- or γ-position to the phenolic OH functional group, b = 1, 2, 3, 4 or 5 It is. When b is 2 or more, the term “independently selected” means that each substituent R of the C ₆ H _5-b nucleus may be the same or different.

Due to the need for rapid and efficient photocuring, the photoinitiator and photosensitizer are freely miscible with the photocrosslinkable composition in which they are formulated, preferably forming a clear solution or at least a stable suspension. It is required to form a suspension or dispersion. In the case of the epoxy-functional and carbinol-functional photocrosslinkable silicones of the present invention, the onium-type cationic photocatalyst must be compatible with these liquid epoxy silicones. To address the miscibility issue, the general formula _{((R-Ph) 2 I} ) + X - iodonium salts have been designed, R represents typically various alkyl-derived dodecylbenzene linear alkylate grade A mixture of fragments, commonly referred to as dodecyl, but not pure dodecyl. Due to the impurities of dodecylbenzene, this compound exhibits a freezing point depression compared to the pure compound and therefore tends to exist in an amorphous, amorphous, semi-liquid state compatible with the epoxy silicone of the present invention. is there. Such a dodecylbenzene-derived diphenyliodonium cation-type photocuring catalyst is well suited for use as a photocatalyst for UV-cured epoxy silicone release systems. Hexafluoroantimonate is most preferred for the composition of the present invention because it tends to have both high activity and excellent miscibility and is not very expensive to manufacture. It has now been found that alkylphenols as reactive diluents are very effective in further promoting complete dissolution of the iodonium salt photocatalyst in the compositions of the present invention.

  The UV curable one-part silicone composition of the present invention can be applied to paper, metal, foil, glass, PEK paper, SCK paper, and other cellulose-based substrates including polyethylene, polypropylene, and polyester films. The epoxy-functional silicone composition of the present invention cures by a UV initiated reaction to form a non-tacky / tack-free surface on the coated substrate.

  The UV curable silicone coating composition of the present invention is a dialkyl epoxy siloxy-terminated linear liquid having a viscosity of about 10 to 1000 centistokes at 25 ° C. effective at catalyzing the UV initiated curing reaction of the silicone coating composition. Fully compatible to promote complete dissolution of the polydialkylsiloxane and dialkyl (carbinol) siloxy-terminated linear liquid polydialkylsiloxane having a viscosity of about 50-5000 centistokes at 25 ° C. and the iodonium salt catalyst in the coating medium In combination with other alkylphenol additives.

  A preferred UV initiator or photocatalyst for use in the present invention is a diaryl iodonium salt derived from "linear alkylate" dodecylbenzene. Such salts have the general formula:

_{((C z H 2z + 1} ) -Ph) 2 -IY
In the formula, z is an integer of about 6 to about 18, Y is SbF ₆ , AsF ₆ , PF ₆ , or BF ₄ , and Ph represents a phenyl group. These bis (4-dodecylphenyl) iodonium salts are very effective initiators for UV curing of a wide range of epoxy functional silicones. Most preferred is Y salt is SbF _6.

“Linear alkylate” dodecylbenzene is known as a commercial product and is produced by Friedel-Crafts alkylation of benzene with a C ₆ -C ₁₄ α-olefin fraction. As a result, these alkylates mainly contain branched dodecylbenzene, but in fact, in addition to other isomers of dodecylbenzene such as ethyldecylbenzene, undecylbenzene, tridecylbenzene, etc. The isomers may be present in large quantities. However, such a mixture is responsible for the dispersion characteristics of the catalyst derived from the linear alkylate, and helps to keep the material in a liquid state. These catalysts are free-flowing viscous liquids at room temperature.

  Bis-dodecylphenyl iodonium salts are very different from the diaryliodonium salts described above. They are pentane soluble and insoluble in water. The improved solubility and catalytic efficiency of these branched chain substituted salts is further emphasized by comparison with similar salts prepared from linear n-tridecylbenzene and n-dodecylbenzene. Specific examples of these salts include bis (4-n-tridecylphenyl) iodonium hexafluoroantimonate having a long-chain linear hydrocarbon. This salt is a waxy solid that does not dissolve in pentane or water and is very slightly dispersed in the epoxy functional silicone utilized in the coating composition of the present invention. When this catalyst is used in a release coating, UV curing is very slow.

  In the UV curable silicone composition of the present invention, an epoxy-terminated linear silicone fluid is used. Epoxy compounds having both unsaturation and oxirane, such as 4-vinylcyclohexene oxide, react with silylhydride functional polysiloxanes by a hydrosilylation reaction. Similar hydrosilylation reactions of vinyl siloxane groups with silylhydride functional polysiloxanes are well known means for crosslinking or curing silicone polymers.

  Epoxy-terminated silicones can also be prepared from olefinic group-containing vinyl- or allyl-functional compounds such as allyl glycidyl ether or glycidyl acrylate, vinyl norbornene monooxide and dicyclopentadiene monoxide. Cyclohexyl epoxy compounds are particularly useful, but other vinyl functional alicyclic epoxies or glycidyl ether compounds can be used without significantly altering the intent of the present invention. The technical scope of the present invention is not limited to the epoxide species used in the examples.

  Epoxy-terminated linear liquid silicones and (poly) carbinol-terminated linear silicones can be made in several ways. The following examples illustrate two such methods, but the invention is not limited to these examples. Referring to these examples, other organofunctional liquid intermediates can be obtained by those skilled in the art. The disclosures of the US patents cited herein are hereby incorporated by reference.

Preparation of organic functional group-terminated silicone
Preparation of polymer A 310 g of dimethylhydrogensiloxy-terminated polydimethylsiloxane having a schematic structure ^MH D ₂₂ ^MH was weighed into a 1 L reaction flask. This polymer was a liquid with a viscosity of 21.7 cstks, contained about 1150 ppm of reactive H, and a total of about 0.36 moles of SiH functional groups were present. A sufficient amount of RhCl ₃ (Bu ₂ S) ₃ in ethanol was added to the polymer to bring the amount of Rh in the polymer to about 5 ppm. This mixture was stirred at 90 ° C., and then 46 g (0.37 mol) of 4-vinylcyclohexene oxide was added dropwise over 15 minutes. An exothermic reaction occurred and the batch temperature rose to 125 ° C. After maintaining at 90 ° C. for 1 hour, the reaction mixture was subjected to infrared analysis, and it was confirmed that H that remained unreacted was less than 10 ppm. 0.03 g of methyldi-cocoamine stabilizer is added to the batch, which is then processed in a laboratory scale thin film evaporator at 200 ° C. and 0.5 torr vacuum for 2 hours to remove excess VCHO and siloxane lighter components. Removed. The final product devolatilized was a liquid having a viscosity of 57.2 cstk, and its non-volatile content was 99.3% according to a weight loss test at 150 ° C. for 45 minutes. Polymer A can be represented as M ^E D ₂₂ M ^E.

Preparation of Polymer B 200 g of dimethylhydrogensiloxy-terminated polydimethylsiloxane having a schematic structure ^MH D ₁₃₀ ^MH was weighed into a 500 mL reaction vessel. This polymer contained about 205 ppm of reactive H and a total of about 0.04 moles of SiH functional groups were present. A sufficient amount of conventional Karstedt platinum hydrosilation catalyst solution was added to give about 5 ppm of Pt, followed by 6.1 g of trimethylolpropane monoallyl ether (0.042 mol). The entire mixture was stirred at 80 ° C. for 2 hours and then infrared spectroscopic analysis revealed no SiH functional groups. The reaction product was subjected to a devolatilization treatment similar to that described for polymer A to finally obtain a polymer liquid having a nonvolatile content of 98.8% and a viscosity of 900 centistokes. Polymer B can be expressed as _{^{M (ROH) 2 D 130 M}} (R0H) 2.

Other ingredients
Alkylphenol additive C
Commercially available alkylphenols consisting of various isomer mixtures of 4-alkylphenols in which the alkyl substituents are distributed from —C ₈ H ₁₇ to —C ₁₄ H ₂₉ centering on “dodecylphenol” were used in the compositions and experiments described below.

Photocatalyst solution D
A commercial product consisting of a 50% bis (4-dodecylphenyl) iodonium hexafluoroantimonate solution in alkyl glycidyl ether called DY-025 from Ciba Specialties was used for the following compositions and experiments.

One-part photocurable silicone composition The blends described below of the above components were prepared by simply mixing the four components. All of these compositions were clear and homogeneous liquids. The charged amount is shown in Table 1.

上記の試験用一液型組成物と併せて、市販ポリエポキシ官能性ジメチルシリコーンポリマーＵＶ９４００（商標）１００部に触媒Ｄを１部を加えた粘度２５０ｃｐｓの対照用混合物を調製した。

A control mixture with a viscosity of 250 cps was prepared by adding 1 part of Catalyst D to 100 parts of a commercially available polyepoxy-functional dimethyl silicone polymer UV9400 ™ in conjunction with the above test one-part composition.

  After the preparation of these experimental and control photocatalytic coating mixtures, the viscosity of each mixture was measured as a function of time when stored in the dark at various temperatures. The point at which the viscosity doubles is an arbitrary measure that defines the shelf life of the solventless reactive silicone coating composition. All samples were cooled to 25 ° C. for viscosity measurements using a Brookfield LVF model viscometer and then returned to the temperature control environment of the experimental procedure. The measurement results are shown in the following table.

４０℃での貯蔵寿命実験で予想外の結果が得られた。ヨードニウム触媒濃度は浴安定性に逆に影響し、ＤＤＰ含有量も同様であった。ポリマーＡとポリマーＢとの比は、スクリーニングしたブレンドの範囲ではたいした影響をもたないことが認められた。４０℃貯蔵寿命の検討結果に基づいて、上述の組成物の所定のものについて室温及び昇温下での安定性試験を実施した。結果を表３〜表５に示す。

Unexpected results were obtained in a shelf life experiment at 40 ° C. The iodonium catalyst concentration adversely affected bath stability, as was the DDP content. The ratio of polymer A to polymer B was found to have no significant effect over the range of blends screened. Based on the examination result of the 40 ° C. storage life, a stability test at room temperature and elevated temperature was performed on a predetermined one of the above-described compositions. The results are shown in Tables 3-5.

上述の貯蔵寿命の研究から、テレケリック反応性線状ポリジメチルシロキサンをベースにしたユニークな処方のブレンドが有用な製品に十分な室温及び高温安定性をもつことが実証された。次いで、試験した一液型ブレンドの薄膜がすべて紫外線露光によって光硬化できることを実証した。試験した組成物Ａ〜Ｈ及び対照ブレンドの各々を、機械仕上紙上にＨＤＰＥを押出して平滑で均一な表面としたものからなる基材（この基材はポリクラフト又はＰＫライナーと呼ばれる）に、ドクターブレードを用いて手作業で塗工して約１．５μｍ厚のコーティングとした。これらのコーティングを、ＲＰＣ Ｌａｂ ＵＶ Ｐｒｏｃｅｓｓｏｒに装着した入力２００Ｗ／ｉｎのＨａｎｏｖｉａ社製中圧水銀ランプからの集束紫外線に露光した。マイグレーションのない不粘着面へとコーティングが硬化する最大コンベヤー速度（最低紫外線露光時間）を確立するためにコンベヤー速度を変化させ、同じランプ及びコンベヤー構成で上記Ｐｒｏｃｅｓｓｏｒを通してＥＩＴ光度計を作動して、得られたＵＶ照射量を記録した。定性的な硬化結果を以下に示す。

The above shelf life studies have demonstrated that a unique blend of formulations based on telechelic reactive linear polydimethylsiloxane has sufficient room and high temperature stability for useful products. It was then demonstrated that all thin films of the one-part blends tested could be photocured by UV exposure. Each of the tested compositions A-H and the control blend was applied to a substrate (this substrate is called a polykraft or PK liner) made of HDPE extruded onto machine-finished paper to a smooth and uniform surface. The coating was performed manually using a blade to obtain a coating having a thickness of about 1.5 μm. These coatings were exposed to focused ultraviolet light from a medium pressure mercury lamp manufactured by Hanovia with an input of 200 W / in attached to an RPC Lab UV Processor. Varying the conveyor speed to establish the maximum conveyor speed (minimum UV exposure time) at which the coating cures to a non-stick surface without migration, operating the EIT photometer through the processor with the same lamp and conveyor configuration Recorded UV dose. The qualitative curing results are shown below.

これらの結果には若干のバラツキはあるものの、ＵＶ光への短時間露光で、すべての組成物が同程度の迅速な光応答を示し、固体不粘着性コーティングへと迅速に架橋したと明言できる。対照ポリマーがその分子鎖にそって多数の脂環式エポキシ基を有するのに対して、一液型剥離コーティングのすべてが連鎖末端にしか反応部位をもたないことに鑑みれば、光硬化応答がほぼ同じという定性的硬化結果は予想外である。

Although there is some variation in these results, it can be stated that all compositions showed a comparable rapid photoresponse and rapidly cross-linked into a solid tack-free coating upon short exposure to UV light. . In view of the fact that the control polymer has a large number of cycloaliphatic epoxy groups along its molecular chain whereas all of the one-part release coatings have reactive sites only at the chain ends, the photocuring response is The qualitative cure results that are about the same are unexpected.

Next, in a coating experiment, this new one-part UV curable composition is easily applied onto a PK liner using conventional coating techniques, and these coatings can be used to release pressure sensitive adhesives during curing. It proved to be effective, that is, to function as a useful release agent. Several of the above compositions were prepared for coating testing on an 18 inch wide pilot coater equipped with a five roll film splitting nip fed coating head. The coating was applied to a PK liner at a line speed of 400 ft / min, and the coated silicone was exposed to a single line of 400 W / in Fusion Systems ™ H lamp and photocured. Inline corona treatment of the PK paper web to about 45 dyn helped the anchoring of the silicone. The coating was required to have a coating weight of 1.0-1.1 g / m ² or a thickness on the order of microns, which suggests that the relatively low viscosity of the one-part coating blend provides good coating weight. It can be seen that control is not impaired. All of the coatings tested cured to a solid with no smear or migration, but this was immediately removed from the line with TESA 7475 acrylic PSA test tape, TESA 4651 rubber PSA test tape and acrylic emulsion PSA commercial label face stock. Affixed to the silicone surface. The tape was peeled from cured liner samples of laminates aged at room temperature or elevated temperature for various times. Using a ZPE1000 High Speed peel test device and a TLMI peel test device, the peel force required to peel the silicone coat liner from the adhesive at an angle of 180 ° at a constant peel rate was recorded.

  Peel stability (as a function of laminate aging) and peel release profile (variation of the force required to peel the liner from the tape as a function of peel rate) were determined. The peeling results are shown in the following Tables 7 to 11.

強粘着性ＴＥＳＡ７４７５アクリル系ＰＳＡテープに対する速度３００ｉｐｍでの剥離力は一液型ＵＶ硬化コーティングの方が対照よりも高かったが、剥離安定性は一液型コーティングの方が対照よりも、特に昇温下で優れていた。

The peel strength at 300 ipm for high tack TESA7475 acrylic PSA tape was higher for the one-part UV curable coating than the control, but the peel stability was particularly higher for the one-part coating than for the control. Excellent under.

試験したすべてのコーティングでアクリルエマルジョン系ＰＳＡフェイスストック構造からの剥離力は一様に低く、この慣用ＰＳＡからの新規一液型ＵＶ硬化剥離コーティングの剥離力は対照ＵＶ硬化エポキシシリコーンコーティングとほぼ同じであったが、さほど安定ではなかった。

The peel force from the acrylic emulsion-based PSA facestock structure is uniformly low for all coatings tested, and the peel strength of the new one-part UV cured release coating from this conventional PSA is approximately the same as the control UV cured epoxy silicone coating. Although it was, it was not so stable.

この場合、硬化一液型組成物の剥離は互いに大きく異なっており、鎖長の長いポリマーＢの含有量の高いコーティング（Ｂ及びＣ）でゴム系ＰＳＡテープに対する３００ｉｐｍでの剥離力が高かったが、これは、コーティングの架橋密度が低く弾性率が低い（エラストマー性の高いシリコーン）こととテープにゴム弾性ＰＳＡを使用したことと符合する。架橋度の高い対照コーティングは、ゴム系ＰＳＡから剥がすときの剥離力が低いことから明らかなように、剛直で高い弾性率挙動を示す。用途毎に様々な剥離挙動が必要とされるので、剥離力の絶対値は剥離安定性ほど重要ではない。

In this case, the peel of the cured one-part composition was greatly different from each other, and the peel strength at 300 ipm against the rubber-based PSA tape was high in the coatings (B and C) having a high content of the polymer B having a long chain length. This is consistent with the low crosslink density of the coating and low elastic modulus (highly elastomeric silicone) and the use of rubber elastic PSA for the tape. A control coating with a high degree of cross-linking exhibits a rigid and high modulus behavior as evidenced by the low peel force when peeled from the rubber-based PSA. Since different peel behaviors are required for each application, the absolute value of the peel force is not as important as the peel stability.

これらの結果は表６に示す３００ｉｎ／ｍｉｎ剥離結果と一致する。剥離速度０．１２５ｍ／ｓは３００ｉｐｍに等しく、剥離速度０．００５ｍ／ｓは約１２ｉｎ／ｍｉｎであり、剥離ライナーの低速「ハンドピール」作業の一般的目安である。代表的な一液型ＵＶ硬化剥離コーティングのピール剥離プロファイルは対照ＵＶ硬化剥離コーティングのものと大きく異なる。低剥離速度（「ハンドピール」）での剥離力に大差ないが、剥離速度が大きくなると、粘着テープから剥離するのに要する力は一液型コーティングの方が対照コ−ティングよりも格段に大きくなる。かかる動的ピール剥離挙動は照射線硬化シリコーン剥離剤では極めて異例であり、照射線硬化シリコーン剥離剤は対照コーティングで観察されるような「フラットな」ピール剥離プロファイルを示すのが一般的である。高速自動ラベリング変換プロセスに用いられる剥離ライナーには、動的ピール剥離プロファイルが極めて望ましい。かかる性能によって、ボトル、箱その他の容器にラベルを貼り付ける前の「早期分配」が防止されるからである。動的ピール剥離プロファイルは、通常は、ジメチルビニル−シロキシ末端線状シリコーンベースポリマーを当業者に周知の通り白金系ヒドロシリル化触媒存在下でポリ（メチルハイドロジェン）シロキサンポリマーで架橋した無溶剤熱硬化シリコーン組成物で得られる。かかる二液型熱硬化性シリコーン剥離剤（ビニル末端線状シリコーンの市販品ＳＬ６６２５５（商標）をベースポリマーとして使用）を、表１から選択した代表的な２種類の一液型ＵＶ硬化剥離剤と対比するため、ＵＶ対照コーティングも併せて、別の実験を実施した。３本ロールオフセットグラビア塗工ヘッドを備えた幅１２インチのパイロットコーターを用いて、約１．２ｇｓｍのシリコーンを塗工した。２．０ミルのポリエステルフィルムを基材として選択し、熱硬化性シリコーンの硬化は、塗工ＰＥＴを１２０℃のオーブンに約３秒の滞留時間で暴露することによって実施した。一液型ＵＶシリコーンコーティング及びＵＶ対照の硬化は、Ｆｕｓｉｏｎ Ｓｙｓｔｅｍｓ（商標）Ｈランプからの約１００ｍＪ／ｃｍ^２の集束ＵＶ線に露光して行った。ＴＥＳＡ７４７５アクリル系試験テープを硬化直後の各コーティングに貼り付け、剥離ライナナー付テープを２５℃で２週間エージングし、上述の通りピール剥離プロファイルを測定した。この実験の結果を表１１にまとめた。

These results agree with the 300 in / min peeling results shown in Table 6. A peel speed of 0.125 m / s is equal to 300 ipm and a peel speed of 0.005 m / s is about 12 in / min, which is a general guideline for the low speed “hand peel” operation of the release liner. The peel release profile of a typical one-part UV cured release coating is significantly different from that of a control UV cured release coating. There is not much difference in the peel force at low peel speed ("hand peel"), but as the peel speed increases, the force required to peel from the adhesive tape is much greater for the one-part coating than for the control coating. Become. Such dynamic peel release behavior is very unusual for a radiation curable silicone release agent, which typically exhibits a “flat” peel release profile as observed in a control coating. A dynamic peel release profile is highly desirable for release liners used in high speed automatic labeling conversion processes. This is because such performance prevents “early dispensing” before labeling a bottle, box or other container. The dynamic peel release profile is usually a solvent-free thermoset of a dimethylvinyl-siloxy-terminated linear silicone-based polymer crosslinked with a poly (methylhydrogen) siloxane polymer in the presence of a platinum-based hydrosilylation catalyst as is well known to those skilled in the art. Obtained with a silicone composition. Such a two-component thermosetting silicone release agent (using a commercially available product SL66255 (trademark of vinyl-terminated linear silicone) as a base polymer) was selected from two typical one-component UV-curable release agents selected from Table 1. For comparison, another experiment was performed with a UV control coating. About 1.2 gsm of silicone was applied using a 12 inch wide pilot coater equipped with a three roll offset gravure coating head. A 2.0 mil polyester film was selected as the substrate and curing of the thermoset silicone was performed by exposing the coated PET to a 120 ° C. oven with a residence time of about 3 seconds. One-part UV silicone coatings and UV control cures were exposed to about 100 mJ / cm ² focused UV radiation from a Fusion Systems ™ H lamp. A TESA 7475 acrylic test tape was affixed to each coating immediately after curing, the tape with release liner was aged at 25 ° C. for 2 weeks, and the peel release profile was measured as described above. The results of this experiment are summarized in Table 11.

本例にみられるように、剛性ＰＥＴライナーからのＰＳＡの剥離力は、ＰＫ型ライナーからの剥離力よりも低い。この観察結果にみられるように熱硬化シリコーンは一液型ＵＶコーティングよりも若干低い剥離力を与えるが、熱対照及び一液型ＵＶ硬化コーティングの動的ピール剥離プロファイルは非常に類似しており、ＵＶ対照コーティングのフラットなプロファイルとは大きく異なる。いうまでもないが、一液型シリコーンコーティングの利便性及び使い易さは、あらゆる市販の無溶剤熱硬化性シリコーン組成物で可能なわけではない。

As seen in this example, the peel force of PSA from the rigid PET liner is lower than the peel force from the PK type liner. As seen in this observation, thermoset silicone gives a slightly lower release force than the one-part UV coating, but the dynamic peel release profiles of the thermal control and one-part UV-curable coating are very similar, It is very different from the flat profile of the UV control coating. Needless to say, the convenience and ease of use of a one-part silicone coating is not possible with all commercially available solventless thermosetting silicone compositions.

Claims (12)

An ultraviolet or electron beam curable silicone coating composition comprising the following components (a) to (d):
_{^{(A) M E D x M}} E, a ^{M GE} D ^x M _^GE, epoxy terminated linear silicone selected from the group consisting of ^_M E D ^x _M ^GE, and mixtures thereof, from about 10 to about at 25 ° C. Epoxy-terminated linear silicone having a viscosity of 1000 centistokes, where M ^E = (C ₆ H ₉ O (CH ₂ CH ₂ ) (CH ₃ ) ₂ SiO _1/2
M ^GE = (CH ₂ (O) CH) O (CH ₂ ) ₃ (CH ₃ ) ₂ SiO _1/2
D = (CH ₃ ) ₂ SiO _2/2 ,
x is 0 or a positive integer. ),
(B) a mono- or polycarbinol-terminated linear silicone selected from the group consisting of M ^ROH D _y M ^ROH and mixtures thereof, having a viscosity of from about 50 to about 5000 centistokes at 25 ° C. Nord-terminated linear silicone,
(In the formula, M ^ROH is HO (CH ₂ ) ₃ (CH ₃ ) ₂ SiO _1/2 , (HOCH ₂ ) ₂ (C ₂ H ₅ ) C—O— (CH ₂ ) ₃ (CH ₃ ) ₂ SiO _{1 / 2} and _{HOCH 2 (HO) CHCH 2 -O-} (CH 2) is selected from ₃ (CH 3) ₂ group consisting of _{SiO 1/2,} y is 0 or a positive integer.),
(C) an effective amount of bis (alkylphenyl), alkylphenyl (phenyl), alkoxyphenyl (phenyl) or bis (alkoxyphenyl) iodonium salt photocatalyst, hexafluoroantimonic acid, hexafluoroarsenic acid, hexafluorophosphoric acid A photocatalyst selected from the salts of the group of acids consisting of tetrafluoroboric acid, tetra (perfluorophenyl) boric acid and mixtures thereof;
(D) an alkylphenol compound selected from the group consisting of R _b —C ₆ H _5-b —OH, wherein R is C ₁ -C ₆₀ straight chain alkyl, C ₃ -C ₆₀ branched alkyl, C ₂ -C ₆₀ are independently selected from monovalent hydrocarbon group selected from straight chain alkenyl and C ₃ -C ₆₀ branched group consisting of alkenyl radical, R groups to the phenolic OH functionality alpha-, beta It may be in either the-or γ-position, b = 1, 2, 3, 4 or 5.) Component (a) is about 50 to about 95% of the composition consisting of components (a), (b), (c) and (d), and component (b) is component (a), (b), ( from about 2 to about 49% of the composition consisting of c) and (d), wherein component (c) is about 0.1% of the composition consisting of components (a), (b), (c) and (d). The component (d) is from about 0.5 to about 10% of the composition comprising components (a), (b), (c) and (d). Composition. Component (a) is about 75 to about 95% of the composition consisting of components (a), (b), (c) and (d), and component (b) is component (a), (b), ( from about 5 to about 25% of the composition comprising c) and (d), wherein component (c) is about 0.5% of the composition comprising components (a), (b), (c) and (d). The composition of claim 1, wherein the composition is about 2% and component (d) is about 1 to about 5% of the composition consisting of components (a), (b), (c) and (d). Component (a) is about 80 to about 95% of the composition consisting of components (a), (b), (c) and (d), and component (b) is component (a), (b), ( about 5 to about 20% of the composition consisting of c) and (d), wherein component (c) is about 0.5% of the composition consisting of components (a), (b), (c) and (d). The composition of claim 1, wherein the composition is about 1% and component (d) is about 2 to about 5% of the composition consisting of components (a), (b), (c) and (d). The composition of claim 1 wherein the epoxy-terminated silicone is ^{M E} _D X ^M E. Component (a) is about 50 to about 95% of the composition consisting of components (a), (b), (c) and (d), and component (b) is component (a), (b), ( from about 2 to about 49% of the composition consisting of c) and (d), wherein component (c) is about 0.1% of the composition consisting of components (a), (b), (c) and (d). The component (d) is from about 0.5 to about 10% of the composition comprising components (a), (b), (c) and (d). Composition. Component (a) is about 75 to about 95% of the composition consisting of components (a), (b), (c) and (d), and component (b) is component (a), (b), ( from about 5 to about 25% of the composition comprising c) and (d), wherein component (c) is about 0.5% of the composition comprising components (a), (b), (c) and (d). 6. The composition of claim 5, wherein said composition is about 2% and component (d) is about 1 to about 5% of the composition consisting of components (a), (b), (c) and (d). Component (a) is about 80 to about 95% of the composition consisting of components (a), (b), (c) and (d), and component (b) is component (a), (b), ( about 5 to about 20% of the composition consisting of c) and (d), wherein component (c) is about 0.5% of the composition consisting of components (a), (b), (c) and (d). 6. The composition of claim 5, wherein the composition is about 1% and component (d) is about 2 to about 5% of the composition consisting of components (a), (b), (c) and (d). Carbinol-terminated silicone is _{^{M (R0H) 2 D y M}} (ROH) 2, The composition of claim 1. Component (a) is about 50 to about 95% of the composition consisting of components (a), (b), (c) and (d), and component (b) is component (a), (b), ( from about 2 to about 49% of the composition consisting of c) and (d), wherein component (c) is about 0.1% of the composition consisting of components (a), (b), (c) and (d). 10. The composition of claim 9, wherein component (d) is from about 0.5 to about 10% of a composition comprising components (a), (b), (c) and (d). Composition. Component (a) is about 75 to about 95% of the composition consisting of components (a), (b), (c) and (d), and component (b) is component (a), (b), ( from about 5 to about 25% of the composition comprising c) and (d), wherein component (c) is about 0.5% of the composition comprising components (a), (b), (c) and (d). 10. The composition of claim 9, wherein the composition is about 2% and component (d) is about 1 to about 5% of the composition consisting of components (a), (b), (c) and (d). Component (a) is about 80 to about 95% of the composition consisting of components (a), (b), (c) and (d), and component (b) is component (a), (b), ( about 5 to about 20% of the composition consisting of c) and (d), wherein component (c) is about 0.5% of the composition consisting of components (a), (b), (c) and (d). 10. The composition of claim 9, wherein the composition is about 1% and component (d) is about 2 to about 5% of the composition consisting of components (a), (b), (c) and (d).